1. Field of the Invention
This invention relates to a crosslinkable, fluorine-containing elastomer composition, and more particularly to a crosslinkable, fluorine-containing elastomer composition, which comprises a fluorine-containing elastomer containing at least one of iodine and bromine in the molecule and an organic peroxide.
2. Description of the Prior Art
Organic peroxide crosslinking of fluorine-containing elastomer has been regarded as more distinguished than the conventional crosslinking procedures such as polyol crosslinking, polyamine crosslinking, etc. because the organic peroxide crosslinked product has distinguished resistances to engine oil, solvent, etc.
As organic peroxide-crosslinkable, fluorine-containing elastomer, those containing both iodine and bromine, or iodine or bromine in the molecule have been proposed by the present applicants and others [U.S. Pat. No. 4,774,302; Japanese patent application Kokai (Laid-open) Nos. 62-232,407, 53-125,491, 60-221,409, 59-20,310, 62-260,807 and 63-308,008; Japanese Patent Publication No. 54-1,585, etc.].
However, an organic peroxide to be used for the crosslinking generates toxic compounds such as methyl iodide (CH.sub.3 I) or methyl bromide (CH.sub.3 Br) derived from the methyl group in the molecule when decomposed, thereby being about a problem that is hardly ignorable in the maintenance of working site or surrounding atmosphere.
In this connection, the present applicant have proposed a peroxide-vulcanizable, fluorine-containing elastomer composition with less generation of CH.sub.3 I or CH.sub.3 Br at the decomposition of an organic peroxide, which comprises a fluorine-containing elastomer containing at least one of iodine and bromine in the molecule and an organic peroxide having a peroxy group represented by the general formula --O--O--C(CH.sub.3).sub.2 R, wherein R is a lower alkyl group, in the molecule and an activation energy of not more than 34.0 Kcal/mole [Japanese Patent Application Kokai (Laid-open) No. Hei 2-43232] and the composition using a sulfur-containing compound so far used as a ruffer additive together the organic peroxide (Japanese Patent Application No. 63-316201).
These proposed compositions can attain the object of effectively lowering the generation of toxic gases satisfactorily, but lower the compression set of vulcanization products as an index of sealing characteristics. Thus, further improvement has been desired.